JP7479920B2 - Optical member, optical scanning device, and image forming apparatus - Google Patents

Description

The present invention relates to optical members, optical scanning devices, and image forming devices such as copiers, multifunction devices, printers, and facsimile machines.

An optical scanning device generally includes a beam detection unit that receives a light beam from a light source (e.g., a laser diode element), and a focusing lens that is disposed on the optical path between the light source and the beam detection unit and focuses the light beam toward the beam detection unit. Such an optical scanning device is configured to detect, by the beam detection unit, the main scanning start timing of the light beam that is emitted from the light source and deflected and scanned in a predetermined main scanning direction by a deflection scanning member.

JP 2001-169168 A

In the optical scanning device, it is possible to share optical components (e.g., focusing lenses) between the image forming devices or optical scanning devices of various models of electronic devices (e.g., various models of image forming devices) that are equipped with an optical scanning device. However, it is not possible to share optical components between various models of image forming devices or optical scanning devices, and dedicated optical components may be used for each model of image forming device or optical scanning device.

In this regard, for example, Patent Document 1 describes that an electronic still camera has multiple pairs of lens sections consisting of a concave lens and a convex lens as optical members, and each lens section has a different surface shape, and therefore the focal length for each combination is different from one another, such as the distance at which close-up photography is possible, the distance at which normal photography is possible, and the distance at which telephoto photography is possible (see paragraph [0037]). However, it does not describe that the optical members are shared by various models of image forming devices or optical scanning devices.

The present invention aims to provide an optical scanning device and an image forming device that can share optical members with various models of image forming devices or optical scanning devices.

In order to solve the above problems, the present invention provides the following optical member, optical scanning device, and image forming apparatus.

(1) Optical Element The optical element according to the present invention is an optical element for refracting a light beam to diverge or converge, the optical element being a single lens made of a transparent material, and comprising at least three pairs of opposing surfaces, one surface for receiving the light beam and the other surface for emitting the incident light beam, each of the three pairs of surfaces being provided with a lens portion, the curvature of the lens portion on one surface of each of the three pairs of surfaces being the same, the curvature of the lens portion on the other surface of each of the three pairs of surfaces being the same, and any one of the lens portions on the multiple surfaces on the one side being refracted by the light beam. the lens portions have a convex spherical surface on the incident side of the light beam, and a concave toroidal surface which has a curvature in one direction and no curvature in a direction perpendicular to the one direction, on the exit side of the light beam, and the lens portions can be selectively arranged on a housing to which the optical member is attached so that the optical member is attached to one of the three pairs of surfaces faces the incident side of the light beam and the corresponding one of the lens portions on the other side face faces the exit side of the light beam, and the lens portions have a convex spherical surface on the incident side of the light beam, and a concave toroidal surface which has a curvature in one direction and has no curvature in a direction perpendicular to the one direction, on the exit side of the light beam, and the respective shortest distances between the optical axis of the lens portion on one side of each of the three pairs of surfaces and a reference side which is any one of the sides surrounding the lens portion are different from each other .

(3) Optical Scanning Device The optical scanning device according to the present invention is characterized by including the optical member according to the present invention.

(4) Image Forming Apparatus The image forming apparatus according to the present invention is characterized by including the optical scanning device according to the present invention.

The present invention has a simple configuration, yet makes it possible for optical components to be shared by various types of image forming devices or optical scanning devices.

1 is a schematic cross-sectional view of an image forming apparatus according to an embodiment of the present invention, as viewed from the front. 2 is a perspective view of the front side of an optical scanning device in the image forming apparatus shown in FIG. 1 as viewed from the upper right. 3 is a perspective view of the rear side of the optical scanning device shown in FIG. 2 as viewed from the upper left. 3 is a perspective view of the optical scanning device shown in FIG. 2 with a top cover removed, as viewed from above on the front side. FIG. 5 is a plan view showing the optical scanning device shown in FIG. 4 . FIG. 2 is an exploded perspective view showing a state in which a lower cover is removed in the optical scanning device. FIG. 2 is a perspective view showing an example of a deflection scanning unit in an optical scanning device. 1 is a plan view showing an example of the configuration of an optical system in an optical scanning device for normal size (A3 size) recording paper. 3 is a perspective view of the optical member according to the first embodiment attached to a support in a housing, as viewed from above on the light beam incident side. FIG. 3 is a perspective view of the optical member according to the first embodiment attached to a support in a housing, as viewed from above on the light beam emission side. FIG. FIG. 9C is a plan view of the optical member shown in FIGS. 9A and 9B. FIG. 2 is a perspective view of the optical member according to the first embodiment, as viewed from one side. FIG. 4 is a perspective view of the optical member according to the first embodiment, as viewed from the other side. FIG. 2 is a plan view of the optical member according to the first embodiment. FIG. 2 is a bottom view of the optical member according to the first embodiment. FIG. 2 is a left side view of the optical member according to the first embodiment. FIG. 2 is a right side view of the optical member according to the first embodiment. FIG. 2 is a front view of the optical member according to the first embodiment. FIG. 2 is a rear view of the optical member according to the first embodiment. 11A and 11B are perspective views of an optical member according to a second embodiment, as viewed from one side and the other side. FIG. 11 is a perspective view of the optical member according to the second embodiment, as viewed from the other side. FIG. 1 is a schematic diagram for explaining a back-illuminated type beam detection structure. FIG. 1 is a schematic diagram for explaining a surface-receiving type beam detection structure. 11 is a plan view showing another example of the configuration of an optical system in an optical scanning device for normal size (A3 size) recording paper. FIG. FIG. 13 is a perspective view showing another example of a deflection scanning unit in the optical scanning device. 1 is a plan view showing an example of a configuration of an optical system of an optical scanning device for a special size (SRA3 size) of recording paper. 11 is a plan view showing another example of the configuration of an optical system in an optical scanning device that is adapted for a special size (SRA3 size) of recording paper. FIG. 18 is a plan view illustrating the configuration of the optical system in the optical scanning device shown in FIGS. 8, 14, 16, and 17 in one diagram. FIG. 11 is a perspective view of an optical member according to a third embodiment, as viewed from one side. FIG. 11 is a perspective view of the optical member according to the third embodiment, as viewed from the other side.

The following describes an embodiment of the present invention with reference to the drawings. In the following description, identical parts are given the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated.

[Image forming apparatus]
1 is a schematic cross-sectional view of an image forming apparatus 100 according to the present embodiment, as viewed from the front. In the figure, the letter X represents the depth direction, the letter Y represents the left-right direction, and the letter Z represents the up-down direction (vertical direction).

The image forming device 100 according to this embodiment is a monochrome image forming device. The image forming device 100 performs image formation processing according to image data read by the image reading device 1 or image data transmitted from an external source. Note that the image forming device 100 may also be a color image forming device that forms multi-color and monochrome images on paper P.

The image forming device 100 includes a document feeder 108 and an image forming device main body 110. The image forming device main body 110 includes an image forming section 102 and a paper transport system 103.

The image forming section 102 includes an optical scanning device 200 (optical scanning unit), a developing unit 2, a photosensitive drum 3 that acts as an electrostatic latent image carrier, a cleaning section 4, a charging device 5, and a fixing unit 7. The paper transport system 103 includes a paper feed tray 81, a manual paper feed tray 82, a discharge roller 31, and a discharge tray 14.

An image reading device 1 for reading an image of an original document G is provided on the top of the image forming device main body 110. The image reading device 1 has an original document placing table 107 on which the original document G is placed. In addition, an original document feeding device 108 is provided above the original document placing table 107. In the image forming device 100, the image of the original document G read by the image reading device 1 is sent to the image forming device main body 110 as image data, and the image is recorded on paper P.

The image forming apparatus main body 110 is provided with a paper transport path S1. A paper feed tray 81 or a manual feed tray 82 supplies paper P to the paper transport path S1. The paper transport path S1 guides the paper P to the discharge tray 14 via the transfer roller 10 and the fixing unit 7. The fixing unit 7 heats and fixes the toner image formed on the paper P to the paper P. Near the paper transport path S1, pickup rollers 11a and 11b, transport roller 12a, registration roller 13, transfer roller 10, heat roller 71 and pressure roller 72 in the fixing unit 7, and discharge roller 31 are arranged.

In the image forming apparatus 100, the paper P supplied from the paper feed tray 81 or the manual paper feed tray 82 is conveyed to the registration roller 13. Next, the paper P is conveyed to the transfer roller 10 at a timing when the registration roller 13 aligns the paper P with the toner image on the photosensitive drum 3. The toner image on the photosensitive drum 3 is transferred onto the paper P by the transfer roller 10. The paper P then passes through the heat roller 71 and the pressure roller 72 in the fixing unit 7, and is discharged onto the discharge tray 14 via the conveying roller 12a and the discharge roller 31. When an image is to be formed on the back side of the paper P as well as the front side, the paper P is conveyed in the opposite direction from the discharge roller 31 to the inverted paper conveying path S2. The paper P passes through the inverted conveying rollers 12b to 12b, and is guided again to the registration roller 13 after being inverted. Then, the paper P is discharged toward the discharge tray 14 after a toner image is formed and fixed on the back side of the paper P in the same manner as the front side.

[Optical scanning device]
FIG. 2 is a perspective view of the front side of the optical scanning device 200 in the image forming apparatus 100 shown in FIG. 1, seen from the upper right. FIG. 3 is a perspective view of the rear side of the optical scanning device 200 shown in FIG. 2, seen from the upper left. FIG. 4 is a perspective view of the optical scanning device 200 shown in FIG. 2, seen from above the front side, with the upper cover 202 removed. FIG. 5 is a plan view showing the optical scanning device 200 shown in FIG. 4. FIG. 6 is an exploded perspective view showing the optical scanning device 200, with the lower cover 204 removed. FIG. 7 is a perspective view showing an example of the deflection scanning unit 220 in the optical scanning device 200. FIG. 8 is a plan view showing an example of the configuration of an optical system in the optical scanning device 200, with specifications for normal size (A3 size) recording paper (paper P).

The optical scanning device 200 includes a housing 201, an input optical system 210, a deflection scanning unit 220 (deflection scanning section), and an output optical system 230.

The incident optical system 210 includes a light source 211 (laser diode element), a collimator lens 212, an aperture member 213, a cylindrical lens 214, and a light source reflection mirror 215. The light source 211 emits a light beam L (laser beam). The collimator lens 212 converts the light beam L from the light source 211 into approximately parallel light and irradiates it on the aperture member 213. The aperture member 213 narrows the light beam L from the collimator lens 212 and irradiates it on the cylindrical lens 214. The cylindrical lens 214 converges the light beam L from the aperture member 213 only in the sub-scanning direction and focuses it on the reflection surface 223a of the deflection scanning member 223 (polygon mirror) via the light source reflection mirror 215. The light source reflection mirror 215 guides the light beam L from the cylindrical lens 214 to the reflection surface 223a of the deflection scanning member 223 (polygon mirror).

The deflection scanning unit 220 includes a deflection scanning board 221, a deflection scanning motor 222 (polygon motor), and a deflection scanning member 223 (rotating polygon mirror). The deflection scanning board 221 is fixed to the flat surface (upper surface) of the lower cover 204 with a plurality of fixing members (screws) SC to SC. A deflection scanning motor 222 is provided on the deflection scanning board 221. A deflection scanning member 223 is fixed to a rotating shaft 222a of the deflection scanning motor 222. The deflection scanning member 223 deflects and scans the light beam L from the light source reflection mirror 215 in a predetermined main scanning direction X1.

The output optical system 230 includes an fθ lens 231, a beam detection reflecting mirror 232, a condenser lens 233 (beam detection lens), and a beam detection unit 234 (Beam Detect sensor (BD sensor)).

The fθ lens 231 is elongated in the main scanning direction X1. The fθ lens 231 receives the light beam L deflected and scanned in the main scanning direction X1 (longitudinal direction W) by the deflection scanning member 223. The beam detection reflection mirror 232 guides the light beam L deflected and scanned by the reflection surface 223a of the deflection scanning member 223 to the condenser lens 233. The beam detection unit 234 detects the main scanning start timing (image writing start timing) of the light beam L.

By the way, when the detection accuracy of the beam detection unit 234 is taken into consideration, it is necessary to make the first optical path length from the deflection scanning member 223 to the scanned body (photosensitive drum 3) and the second optical path length from the deflection scanning member 223 to the beam detection unit 234 equal or approximately equal to make the beam diameter of the light beam L irradiated by the photosensitive drum 3 equal or approximately equal to the beam diameter of the light beam L irradiated by the beam detection unit 234. However, in this example, the first optical path length is longer than the second optical path length. For this reason, the light beam L from the beam detection reflection mirror 232 is condensed to the beam detection unit 234 using the condenser lens 233. As a result, even if the first optical path length is longer than the second optical path length, the beam diameter of the light beam L at the photosensitive drum 3 and the beam diameter of the light beam L at the beam detection unit 234 can be made equal or approximately equal. Here, the condenser lens 233 can tolerate a certain degree of misalignment of the optical axis of the light beam L.

The housing 201 has a rectangular bottom plate 201a and four side plates 201b to 201e surrounding the bottom plate 201a. The housing 201 is provided with a deflection scanning chamber 203 (see Figures 4 to 6) that covers the deflection scanning unit 220. An opening 203a (see Figure 6) is provided in the deflection scanning chamber 203 portion of the bottom plate 201a. The opening 203a is closed by a bottom cover 204, and the bottom cover 204 is fixed to the bottom surface (lower surface) side of the bottom plate 201a with a plurality of fixing members (screws) SC to SC. The deflection scanning unit 220 is disposed on the bottom cover 204, and the deflection scanning unit 220 is accommodated in the deflection scanning chamber 203 by fixing the bottom cover 204 to the bottom plate 201a. This allows the deflection scanning unit 220 to be replaced by replacing the lower cover 204 with a different deflection scanning unit 220, as described below.

The light beam L reflected by the light source reflection mirror 215 is incident on the inside of the deflection scanning chamber 203 through the first window 203b (see FIG. 5) formed in the deflection scanning chamber 203. The light beam L scanned by the deflection scanning member 223 is emitted to the outside of the deflection scanning chamber 203 through the first window 203b. The first window 203b is provided with a first dustproof glass plate 235 (transparent body). This effectively prevents dust and other unwanted substances from entering the deflection scanning chamber 203. The light beam L passing through the fθ lens 231 is emitted to the outside of the housing 201 through a second window 201f formed in the side plate 201e on the fθ lens 231 side of the housing 201. The second window 201f is provided with a second dustproof glass plate 236 (transparent body). This effectively prevents dust and other unwanted substances from entering the housing 201.

The optical scanning device 200 further includes a substrate 240 (substrate for the light source and the beam detection unit). The light source 211 and the beam detection unit 234 are provided on the substrate 240. The substrate 240 is a flat printed circuit board and has a circuit for driving the light source 211. The substrate 240 is fixed to the outside of the side plate 201d of the housing 201 on the opposite side to the fθ lens 231 so that the emission part of the light source 211 and the light receiving part of the beam detection unit 234 face the inside of the housing 201 through respective openings (not shown) formed in the side plate 201d. This allows the light source 211 to emit the light beam L from the emission part toward the collimator lens 212 in the housing 201. The beam detection unit 234 can receive the light beam L from the condenser lens 233 in the housing 201 at the light receiving part.

The deflection scanning board 221 is a flat printed circuit board and has a circuit that drives the deflection scanning motor 222. The deflection scanning motor 222 is fixed onto the deflection scanning board 221, and the center of the deflection scanning member 223 is connected and fixed to the rotation shaft 222a of the deflection scanning motor 222. The deflection scanning member 223 is rotated by the deflection scanning motor 222.

Next, we will explain the optical path of the light beam L from the light source 211 until it is incident on the photosensitive drum 3.

The light beam L of the light source 211 passes through the collimator lens 212 to be made into a substantially parallel light, narrowed by the aperture member 213, passes through the cylindrical lens 214, enters the light source reflection mirror 215, is reflected, and enters the reflection surface 223a of the deflection scanning member 223. The deflection scanning member 223 is rotated in a predetermined rotation direction R at a constant angular velocity by the deflection scanning motor 222, sequentially reflects the light beam L at each reflection surface 223a, and repeatedly deflects the light beam L at a constant angular velocity in the main scanning direction X1. The fθ lens 231 focuses the light beam L to a predetermined beam diameter on the surface of the photosensitive drum 3 in both the main scanning direction X1 and the sub-scanning direction. The fθ lens 231 also converts the light beam L deflected at a constant angular velocity in the main scanning direction X1 by the deflection scanning member 223 so that it moves at a constant linear velocity on the photosensitive drum 3. This allows the light beam L to repeatedly scan the surface of the photosensitive drum 3 in the main scanning direction X1.

In addition, the optical scanning device 200 detects the main scanning start timing of the light beam L emitted from the light source 211 and deflected in the main scanning direction X1 by the deflection scanning member 223 by the beam detection unit 234. The beam detection unit 234 receives the light beam L reflected by the beam detection reflection mirror 232 just before the main scanning (writing) of the photosensitive drum 3 starts. The beam detection unit 234 receives the light beam L at the timing just before the main scanning of the surface of the photosensitive drum 3 starts, and outputs a BD signal indicating the timing just before the start of the main scanning. The start timing of the main scanning of the photosensitive drum 3 where the toner image is formed is set in response to this BD signal, and writing of the light beam L according to the image data is started. Then, the two-dimensional surface (circumferential surface) of the photosensitive drum 3 which is rotated and charged is scanned by the light beam L, and each electrostatic latent image is formed on the surface of the photosensitive drum 3.

The closer the angle of incidence of the light beam L incident on the first dustproof glass plate 235 is to a right angle, the more the light transmittance can be improved. In this regard, since the light beam L is scanned in the main scanning direction X1, for example, if the first dustproof glass plate 235 is provided along the longitudinal direction W of the fθ lens 231, the following inconvenience occurs. That is, the light beam L (light beam L from the deflection scanning member 223 toward the beam detection unit 234) that is outside the scanning area α (see FIG. 8) from the scanning start position to the scanning end position of the light beam L by the deflection scanning member 223 on the first dustproof glass plate 235 is too inclined with respect to the first dustproof glass plate 235, and therefore the light transmittance is deteriorated.

In this regard, in the present embodiment, the first dustproof glass plate 235 is inclined toward the beam detection unit 234 with respect to the longitudinal direction W of the fθ lens 231. This not only avoids deterioration of the optical transparency of the light beam L in the scanning area α through the first dustproof glass plate 235, but also avoids deterioration of the optical transparency of the light beam L traveling from the deflection scanning member 223 toward the beam detection unit 234 through the first dustproof glass plate 235. In addition, the deflection scanning substrate 221 is disposed parallel or approximately parallel to the first dustproof glass plate 235.

[About this embodiment]
The optical scanning device 200 according to the present embodiment includes an optical member for refracting the light beam L to diverge or converge. Materials that can be used for the optical member include glass materials and transparent resin materials, such as, but not limited to, acrylic resin and polycarbonate. In this example, the optical member is a condenser lens 233 that refracts and converges the light beam L.

First Embodiment
9A and 9B are perspective views of the optical member (233) according to the first embodiment attached to the support portion 250 in the housing 201, respectively, viewed from above on the incident side and the exit side of the light beam L. FIG. 9C is a plan view of the optical member (233) shown in FIG. 9A and FIG. 9B. FIG. 10A and FIG. 10B are perspective views of the optical member (233) according to the first embodiment, respectively, viewed from the surfaces 233A, 233B, and 233C on one side and the surfaces 233a, 233b, and 233c on the other side. FIG. 11A to FIG. 11F are six-sided views of the optical member (233) according to the first embodiment.

The optical member (233) has at least three pairs of opposing surfaces (233A, 233a), (233B, 233b), and (233C, 233c).

The three pairs of surfaces (233A, 233a), (233B, 233b), and (233C, 233c) each have a lens portion (2331A, 2331a), (2331B, 2331b), and (2331C, 2331c).

In the first embodiment, as shown in FIG. 10A, the optical member (233) has three pairs of surfaces (233A, 233a), (233B, 233b), and (233C, 233c), and the lens portions 2331A, 2331B, and 2331C on one side of each pair of surfaces 233A, 233B, and 233C have the same curvature (lens shape). In this example, the lens portions 2331A, 2331B, and 2331C on one side of the surfaces 233A, 233B, and 233C are all spherical lenses. Specifically, the curvature of the lens portions 2331A, 2331B, and 2331C is 0.0446 [1/mm] (radius of curvature 22.4 [mm]). The lens portions 2331A, 2331B, and 2331C may be aspheric lenses. In this case, the curvature can be, for example, the curvature with the position of the optical axis as the reference point.

In the first embodiment, the optical member (233) can have, for example, a lens portion 2331A on one surface 233A as the incident side of the light beam L, and a lens portion 2331a on the other surface 233a as the exit side of the light beam L, as shown in Figures 9A to 9C.

In addition, although not shown in the figure, the optical member (233) can have, for example, a lens portion 2331B on one surface 233B or a lens portion 2331C on one surface 233C as the incident side of the light beam L, and a lens portion 2331b on the other surface 233b or a lens portion 2331c on the other surface 233c as the exit side of the light beam L.

Thus, according to the first embodiment, the optical member (233) has at least three pairs of opposing surfaces (233A, 233a), (233B, 233b), and (233C, 233c), and therefore has a simple configuration. Moreover, since the optical member (233) only requires the positioning of the optical member (233), no adjustment work is required. Then, by directing any one of the lens portions 2331A, 2331B, and 2331B on the multiple surfaces 233A, 233B, and 233C on one side to the incident side of the light beam L, the corresponding lens portion of the lens portions 2331a, 2331b, and 2331c on the surfaces 233a, 233b, and 233c on the other side can be directed to the exit side of the light beam L. Therefore, the optical member can be shared by various types of image forming devices or optical scanning devices.

In this example, the optical member (233) has three pairs of surfaces (233A, 233a), (233B, 233b), and (233C, 233c), and the lens portions 2331A, 2331B, and 2331C on one side of each pair of surfaces 233A, 233B, and 233C have the same curvature (lens shape), but the lens portions 2331a, 2331b, and 2331c on the other side of each pair (see FIG. 10B) have different lens shapes. In this example, the lens portions 2331c, 2331c, and 2331c on the other side all have the same lens shape and are toroidal surface-shaped lenses. A toroidal surface is a surface that has a curvature in one direction (width direction T in this example) but does not have a curvature in a direction perpendicular to the direction (height direction H in this example). Here, the width direction T is a direction perpendicular to both the height direction H and the optical axis direction S, which are the directions on the installation side and the opposite side to the installation side in the housing 201. The optical member (233) has the same curvatures of the lens portions 2331a , 2331b , and 2331c on the other side surfaces 233a, 233b , and 233c. Specifically, the curvatures of the lens portions 2331a , 2331b, and 2331c are all 0.0190 [1/mm] (radius of curvature 52.6 [mm]).

This allows the light beam L to be focused in one direction (the width direction T in this example).

In this embodiment, the optical member (233) has three pairs of surfaces (233A, 233a), (233B, 233b), and (233C, 233c) in which at least one of the lens portions (2331A, 2331a), (2331B, 2331b), and (2331C, 2331c) is a convex lens portion. In this example, the lens portions 2331A, 2331B, and 2331C in the surfaces 233A, 233B, and 233C on one side are all convex lenses. The convex lens portions (2331A, 2331B, and 2331C) do not protrude from the surfaces (233A, 233B, and 233C) on which the convex lens portions (2331A, 2331B, and 2331C) are provided. In more detail, the convex lens portions (2331A, 2331B, 2331C) have their apexes flush with the surfaces (233A, 233B, 233C) or are located inside the surfaces (233A, 233B, 233C).

By doing so, the surfaces (233A, 233B, 233C) of the convex lens portions (2331A, 2331B, 2331C) can be reliably brought into contact with the installation surface (in this example, the bottom surface 201g of the housing 201) without being obstructed by the convex lens portions (2331A, 2331B, 2331C). This allows the optical member (233) to be reliably mounted on the housing 201 while realizing a compact structure for the optical member (233).

More specifically, the optical member (233) has an outer frame portion 2333 (outer portion) provided on the outer periphery of the lens portions (2331A, 2331a), (2331B, 2331b), and (2331C, 2331c).

In this embodiment, a cube is formed by three pairs of faces (233A, 233a), (233B, 233b), and (233C, 233c).

This makes it possible to make the optical element (233) more compact, and thus to reduce the size of the optical scanning device 200.

More specifically, the outer frame portion 2333 of the optical member (233) has a cubic shape. Specifically, the dimensions e1, e2, and e3 (see FIG. 10A) of the sides of the outer frame portion 2333 in the optical axis direction S, width direction T, and height direction H are all 12 mm.

As shown in Figures 5 and 9A to 9C, the housing 201 is provided with a support section 250 that supports the optical member (233). The support section 250 is provided with a number of positioning sections 251 to 256 that position the optical member in the optical axis direction S [the incident direction M1 of the light beam L to the optical member (233)] and the width direction T (the orthogonal direction M2 perpendicular to the incident direction M1).

This allows the optical member (233) to be reliably fixed in the same position on the housing 201 (a common position regardless of which side of the optical member (233) it is installed on).

More specifically, the support section 250 supports the optical member (233) such that the surface to be installed is in contact with the installation surface (in this example, the bottom surface 201g of the housing 201). The multiple positioning sections 251 to 256 define the position in the optical axis direction S (in this example, the direction opposite to the incident direction M1) and the width direction T.

In this embodiment, the shortest distances DA, DB, DC (see Figure 10A) between the optical axis NA, NB, NC (center of curvature) of lens portion 2331A, 2331B, 2331C on one side surface 233A, 233B, 233C of each of the three pairs of surfaces (233A, 233a), (233B, 233b), (233C, 233c) and the reference side TA, TB, TC, which is one of the sides surrounding lens portion 2331A, 2331B, 2331C, are all the same. In addition, the shortest distances Da, Db, Dc (see FIG. 10B) between the optical axes Na, Nb, Nc (centers of curvature) of the lens portions 2331a, 2331b, 2331c on the other side surfaces 233a, 233b, 233c and the reference sides Ta, Tb, Tc, which are any one of the sides surrounding the lens portions 2331a, 2331b, 2331c, respectively, are all the same.

In this example, the reference sides TA, TB, and TC are the sides on one side in the width direction T when the surface to be installed among the surfaces of the optical member (233) is installed in the housing 201. Specifically, the shortest distances (DA, DB, DC), (Da, Db, Dc) are all 6 mm.

By doing this, when the surface to be installed among the surfaces of the optical member (233) is installed in the housing 201, the distance between the optical axes NA, NB, NC and the reference sides TA, TB, TC can be made the same. This makes it possible to use it preferably when the incident position of the light beam L is the same in each model of optical scanning device.

In this embodiment, the shortest distances (DA, DB, DC) and (Da, Db, Dc) may be different from each other. For example, the shortest distances (DA, DB, DC) and (Da, Db, Dc) may be 6 mm, 5 mm, and 4 mm, respectively.

By doing this, when the surface to be installed among the surfaces of the optical member (233) is installed in the housing 201, the distances between the optical axes NA, NB, NC and the reference sides TA, TB, TC can be made different from each other. This makes it possible to use it preferably when the incident positions of the light beam L are different from each other in each model of optical scanning device.

In addition, in this embodiment, the optical member (233) is used as a focusing lens.

By doing so, the optical member (233) can function, for example, as a focusing lens that focuses the light beam L from the deflection scanning member 223 toward the beam detection unit 234.

Second Embodiment
12A and 12B are perspective views of an optical member (233) according to the second embodiment, viewed from surfaces 233A, 233B, and 233C on one side and surfaces 233a, 233b, and 233c on the other side, respectively.

The optical scanning device 200 according to the second embodiment differs from the optical scanning device 200 according to the first embodiment in that the curvatures of the lens portions 2331A, 2331B, 2331C on the surfaces 233A, 233B, 233C on one side of each pair of surfaces of at least two pairs (three pairs in this example) of the three pairs of surfaces (233A, 233a), (233B, 233b), (233C, 233c) are different from each other. In this example, the curvatures of the lens portions 2331a, 2331b, 2331c on the surfaces 233a, 233b, 233c on the other side are different from each other. Specifically, the curvatures of the lens portions 2331A, 2331B, and 2331C are 0.0446 [1/mm] (radius of curvature 22.4 [mm]), 0.0394 [1/mm] (radius of curvature 25.4 [mm]), and 0.0515 [1/mm] (radius of curvature 19.4 [mm]), respectively. The curvatures of the lens portions 2331a, 2331b, and 2331c are 0.0190 [1/mm] (radius of curvature 52.6 [mm]), 0.0202 [1/mm] (radius of curvature 49.6 [mm]), and 0.01799 [1/mm] (radius of curvature 55.6 [mm]), respectively. The curvatures of lens portions 2331A, 2331B, and 2331C may be different from one another, and the curvatures of lens portions 2331a, 2331b, and 2331c may be the same.

By doing this, the focal lengths of lens sections 2331A, 2331B, and 2331C can be made different from each other.

Moreover, in the optical member (233) of the second embodiment, the optical axes NA, NB, NC of the lens portions 2331A, 2331B, 2331C on one side of each pair of surfaces 233A, 233B, 233C of at least two pairs of surfaces (233A, 233a), (233B, 233b), (233C, 233c) are different from each other in terms of the shortest distances DA, DB, DC (see FIG. 12A) between the optical axes NA, NB, NC of the lens portions 2331A, 2331B, 2331C and reference sides TA, TB, TC, which are any one of the sides surrounding the surfaces including the lens portions. In addition, the shortest distances Da, Db, Dc (see FIG. 12B) between the optical axes Na, Nb, Nc of the lens portions 2331a, 2331b, 2331c on the other side surfaces 233a, 233b, 233c and the reference sides Ta, Tb, Tc, which are any one of the sides surrounding the lens portions 2331a, 2331b, 2331c, are different from each other. Specifically, the shortest distances (DA, DB, DC), (Da, Db, Dc) are 6 mm, 5 mm, and 4 mm, respectively.

By doing this, when the surface to be installed among the surfaces of the optical member (233) is installed in the housing 201, the distances between the optical axes NA, NB, NC and the reference sides TA, TB, TC can be made different from each other. This makes it possible to use it preferably when the incident positions of the light beam L are different from each other in each model of optical scanning device.

Next, a configuration example in which the curvatures of the lens portions 2331A, 2331B, and 2331C are different from each other will be described below with reference to Figures 8, 13A, 13B, and 14.

Figure 13A is a schematic diagram for explaining a back-side light receiving type beam detection structure, and Figure 13B is a schematic diagram for explaining a front-side light receiving type beam detection structure. Figure 14 is a plan view showing another example of the configuration of an optical system in optical scanning device 200 for normal size (A3 size) recording paper (paper P).

However, depending on the type of beam detection unit 234, the incident position in the optical axis direction S (incident direction M1 in which the light beam L is incident), which is the direction of the optical axis N, may differ. For example, the beam detection unit 234 may have a front-side light receiving type beam detection structure and a back-side light receiving type beam detection structure. In this embodiment, it is possible to attach multiple types of beam detection units 234 that differ from each other in the incident position in the incident direction M1 in which the light beam L is incident.

The optical scanning device 200 is equipped with a substrate 240, which may be a back-side light receiving substrate 241 (double-sided substrate or multi-layer substrate) or a front-side light receiving substrate 242 (single-sided substrate), depending on the model of the image forming device 100.

The backside light receiving board 241 (board 240) has a conductor pattern formed on both sides (front and back). As shown in FIG. 13A, the beam detection unit 234 provided on the backside light receiving board 241 (board 240) may be mounted, for example, on the backside 240b of the backside light receiving board 241 [double-sided board or multi-layer board (four-layer board)] so that the light receiving unit 234a faces the opposite side to the backside 240b. Also, the frontside light receiving board 242 (board 240) has a conductor pattern formed only on one side (front side). As shown in FIG. 13B, the beam detection unit 234 provided on the frontside light receiving board 242 (board 240) may be mounted, for example, on the frontside 240a of the frontside light receiving board 242 (single-sided board) so that the light receiving unit 234a (light receiving surface) faces the through hole 240c provided in the frontside light receiving board 242 (single-sided board). In this case, if the back-side light receiving substrate 241 (double-sided substrate or multi-layer substrate) and the front-side light receiving substrate 242 (single-sided substrate) are attached at the same position in the incident direction M1, the positions of the light receiving portions 234a in the incident direction M1 will differ between the beam detection portion 234 provided on the back-side light receiving substrate 241 and the beam detection portion 234 provided on the front-side light receiving substrate 242. For this reason, the focal length d1 of the light beam L to the light receiving portion 234a of the beam detection portion 234 by the optical member (233) in the back-side light receiving type beam detection structure shown in Fig. 13A will differ from the focal length d2 of the light beam L to the light receiving portion 234a of the beam detection portion 234 by the optical member (233) in the front-side light receiving type beam detection structure shown in Fig. 13B (d1<d2). In this case, if the focal position of the optical member (233) is adjusted to the focal length d1 or focal length d2 of the beam detection unit 234 in either the back-side light receiving type beam detection structure or the front-side light receiving type beam detection structure, the focal position of the optical member (233) in the other beam detection structure will not be adjusted, and the beam detection accuracy of the beam detection unit 234 will deteriorate.

In this regard, in the optical scanning device 200 according to the present embodiment, the lens sections 2331A, 2331B, and 2331C have different curvatures, so that the focal lengths of the lens sections 2331A, 2331B, and 2331C can be made different from one another. In other words, the focal length d1 shown in FIG. 13A and the focal length d2 shown in FIG. 13B can be made different, which effectively prevents deterioration of the beam detection accuracy of the beam detection structure.

Next, an example of a configuration in which the shortest distances (DA, DB, DC) and (Da, Db, Dc) are different from each other will be described below with reference to Figures 7, 8, and 14 to 18.

Figure 15 is a perspective view showing another example of the deflection scanning unit 220 in the optical scanning device 200. Figures 16 and 17 are plan views showing an example and another example of the optical system configuration in the optical scanning device 200 with specifications for a special size (SRA3 size) of recording paper (paper P), respectively. Also, Figure 18 is a plan view that combines the optical system configurations in the optical scanning device 200 shown in Figures 8, 14, 16, and 17 into a single diagram.

A deflection scanning motor 222 (first deflection scanning motor 2221, second deflection scanning motor 2222) is provided on the deflection scanning board 221. A deflection scanning member 223 (first deflection scanning member 2231, second deflection scanning member 2232) is fixed to the rotation shaft 222a of the deflection scanning motor 222 (2221, 2222). The deflection scanning member 223 (2231, 2232) deflects and scans the light beam L from the light source reflection mirror 215 in a predetermined main scanning direction X1.

In the optical scanning device 200, the size in the main scanning direction X1 of the reflecting surface 223a of the deflection scanning member 223 (second deflection scanning member 2232) of the deflection scanning unit 220 (2202) shown in Figures 15 to 18 is larger than the size in the main scanning direction X1 of the reflecting surface 223a of the deflection scanning member 223 (first deflection scanning member 2231) of the deflection scanning unit 220 (2201) shown in Figures 7, 8, 14 and 18. In the optical scanning device 200, the deflection scanning unit 220 (2201) shown in Figures 7, 8, 14, and 18 can be replaced with the deflection scanning unit 220 (2202) shown in Figures 15 to 18 by replacing the lower covers 204, 204 on which the deflection scanning unit 220 (2201, 2202) is provided.

In this regard, in the optical scanning device 200 according to the present embodiment, multiple types of deflection scanning members 223-223 each having a reflection surface 223a-223a of different sizes in the main scanning direction X1 are replaceable as the deflection scanning member 223. In this way, multiple types of deflection scanning members 223-223 each having a reflection surface 223a-223a of different sizes in the main scanning direction X1 can be provided in the optical scanning device 200. In this example, the first deflection scanning member 2231 shown in FIG. 7 has a reflection surface 223a of a predetermined first size in the main scanning direction X1. The second deflection scanning member 2232 shown in FIG. 15 has a reflection surface 223a of a predetermined second size larger than the first size in the main scanning direction X1 of the first deflection scanning member 2231 shown in FIG. 7.

In addition, when the optical scanning device 200 is used with image forming devices of various models having different sizes of scanning area α (α1, α2) (see Figures 8, 14, 16 to 18) from the scanning start position to the scanning end position of the light beam L deflected and scanned by the deflection scanning member 223, for example, when the optical scanning device 200 is used with image forming devices of various models having different specifications for the size of the recording paper (paper P) [A3 size (297 mm x 420 mm) and SRA3 size (320 mm x 450 mm)], it is necessary to provide the optical scanning device 200 with multiple types of deflection scanning members 223 each having a reflection surface 223a of different sizes in the main scanning direction X1.

In this case, from the viewpoint of miniaturization of the housing 201, the reflecting mirror (232) is provided near the outside of the scanning area α (α1, α2), so the position of the reflecting mirror (232) is changed between the first scanning area α1 and the second scanning area α2. Then, the angle of incidence of the light beam L to the reflecting mirror (232) changes, so it is necessary to change the mirror arrangement angle θ (θ1, θ2). In this example, the second scanning area α2 is larger than the first scanning area α1. Specifically, the first scanning area α1 is a scanning area by the first deflection scanning member 2231, and the width (width of the image area) of the scanning surface of the scanned body (photosensitive drum 3) is 310 mm. In addition, the second scanning area α2 is a scanning area by the second deflection scanning member 2232, and the width (width of the image area) of the scanning surface of the scanned body (photosensitive drum 3) is 330 mm. Therefore, the position (second position) of the reflecting mirror (232) in the second scanning region α2 is located outside the position (first position) of the reflecting mirror (232) in the first scanning region α1. As a result, the position and mirror position angle θ (θ1, θ2) of the reflecting mirror (232) are different between the first scanning region α1 and the second scanning region α2.

However, if the optical path length from the light source 211 to the beam detection unit 234 differs between the first and second placement positions of the reflecting mirror (232) to an extent that exceeds the performance tolerance level (particularly the tolerance level for misalignment of the optical axis) of the optical element (particularly the focusing lens 233), it is difficult to maintain the performance of the optical scanning device 200 unless the position of the optical axis of the optical element (233) is changed.

In this regard, in the optical scanning device 200 according to the present embodiment, the shortest distances (DA, DB, DC) and (Da, Db, Dc) are different from each other. This allows the position of the optical axis in the width direction T of the optical member (233) to be changed, thereby maintaining the performance of the optical scanning device 200.

Third Embodiment
19A and 19B are perspective views of an optical member (233) according to the third embodiment, viewed from surfaces 233A, 233B, and 233C on one side and surfaces 233a, 233b, and 233c on the other side, respectively.

The optical scanning device 200 according to the third embodiment differs from the optical scanning device 200 according to the first embodiment in that the curvatures of all the lens portions (2331A, 2331a), (2331B, 2331b), (2331C, 2331c) in the three pairs of surfaces (233A, 233a), (233B, 233b), (233C, 233c) are the same. In addition, in the third embodiment, the optical member is used as another lens instead of the condenser lens 233. Representative examples of the other lens than the condenser lens include a collimator lens and a cylindrical lens.

In this example, as shown in Figures 19A and 19B, the lens portions (2331A, 2331a), (2331B, 2331b), and (2331C, 2331c) all have the same lens shape and are spherical lenses. Specifically, the curvature of the lens portions (2331A, 2331a), (2331B, 2331b), and (2331C, 2331c) is all 0.0446 [1/mm] (radius of curvature 22.4 [mm]).

In this way, by making the curvatures of all the lens portions (2331A, 2331a), (2331B, 2331b), (2331C, 2331c) in the three pairs of surfaces (233A, 233a), (233B, 233b), (233C, 233c) the same, the lens can be suitably used for various lenses in image forming devices (especially optical scanning devices).

In the third embodiment, the curvatures of the lens portions (2331A, 2331a), (2331B, 2331b), and (2331C, 2331c) may be different. The lens portions (2331A, 2331a), (2331B, 2331b), and (2331C, 2331c) may be aspheric lenses or toroidal lenses. In addition, the shortest distances (DA, DB, DC) and (Da, Db, Dc) may be the same or different from each other.

Other Embodiments
In the first to third embodiments, the reference sides TA, TB, and TC are defined as sides on one side in the width direction T when the surface to be installed among the surfaces of the optical member (233) is installed in the housing 201, but they may be sides on one side in the height direction H. Also, the optical member (233) is used as a light condenser, but it may be used as a light diverger.

In the first to third embodiments, for example, the optical member may be used as a collimator lens. In this case, the optical member can function as a collimator lens that converts the incident light beam L into approximately parallel light. The optical member may be used as a cylindrical lens. In this case, the optical member can function as a cylindrical lens that converges the incident light beam L only in the sub-scanning direction. In addition to these, for example, the optical member in an optical scanning device or an image forming device other than an optical scanning device can be used together with an auxiliary lens that is provided between various lenses and assists the optical characteristics of various lenses in the optical scanning device. The optical member itself may be used as an auxiliary lens for the optical member in an image forming device other than a scanning device or an optical scanning device.

In any case, at least two of the configurations of the first to third embodiments may be combined.

The present invention is not limited to the above-described embodiment, but can be embodied in various other forms. Therefore, the embodiment is merely illustrative in all respects and should not be interpreted in a restrictive manner. The scope of the present invention is indicated by the claims, and is not restricted in any way by the text of the specification. Furthermore, all modifications and changes within the equivalent scope of the claims are within the scope of the present invention.

100 Image forming apparatus 200 Optical scanning device 211 Light source 212 Collimator lens 214 Cylindrical lens 215 Light source reflection mirror 223 Deflection scanning member 231 fθ lens 232 Beam detection reflection mirror 233 Condenser lens (optical member)
2331A-C Lens portion 2331a-c on one side Lens portion 2333 on the other side Outer frame portion 233A-C Surfaces on one side 233a-c Surface on the other side 234 Beam detection portion 240 Board 241 Back surface light receiving board 242 Front surface light receiving board 250 Support portions 251-256 Positioning portions DA-DC Shortest distance Da-Dc Shortest distance H Height direction L Light beam M1 Incident direction M2 Orthogonal direction N Optical axes NA-NC Optical axes Na-Nc Optical axis R Rotation direction S Optical axis direction TA-TC Reference sides Ta-Tc Reference side T Width direction W Longitudinal direction X1 Main scanning directions d1, d2 Focal lengths e1-e3 Dimension α Scanning area α1 First scanning area α2 Second scanning area θ, θ1, θ2 Mirror arrangement angle

Claims (7)

An optical element for refracting a light beam to diverge or converge,
the optical member is a single lens made of a transparent material;
The optical fiber has at least three pairs of opposing surfaces, each pair being an incident surface for the light beam and an exit surface for the incident light beam;
Each of the three pairs of surfaces is provided with a lens portion,
the curvature of the lens portion on one surface of each of the three pairs of surfaces is the same;
the curvature of the lens portion on the other surface of each of the three pairs of surfaces is the same;
the lens portions on the first surface are selectively arranged on a housing to which the optical member is attached so that one of the lens portions on the first surface faces an incident side of the light beam, and a corresponding one of the lens portions on the second surface faces an exit side of the light beam,
the lens portion has a convex spherical surface on an incident side of the light beam, and a concave toroidal surface on an exit side of the light beam that has a curvature in one direction and has no curvature in a direction perpendicular to the one direction ,
An optical element characterized in that the shortest distances between the optical axis of the lens portion and a reference side, which is one of the sides surrounding the lens portion, on one side of each of the three pairs of surfaces are different from each other. 2. The optical member according to claim 1 ,
An optical member, wherein the lens portion having the convex spherical surface does not protrude from the surface on which the lens portion having the convex spherical surface is provided. 3. The optical member according to claim 1 ,
An optical member, wherein the three pairs of faces form a cube. An optical scanning device comprising the optical member according to any one of claims 1 to 3 . 5. The optical scanning device according to claim 4 ,
An optical scanning device, characterized in that the optical member is used as a condenser lens. 6. The optical scanning device according to claim 4 ,
the optical member receives a light beam emitted from a light source and deflected and scanned in a predetermined main scanning direction by a deflection scanning member;
The optical scanning device according to claim 1 , wherein the deflection scanning member is a replaceable deflection scanning member of a plurality of types, each having a reflecting surface of a different size in the main scanning direction. 7. An image forming apparatus comprising the optical scanning device according to claim 4 .

Images